Yi Jian

Low-Timing-Jitter Single-Photon Detection Using 1-GHz Sinusoidally Gated InGaAs/InP Avalanche Photodiode

We demonstrate an efficient way to improve the timing jitter of sine-wave gated InGaAs/InP avalanche photo diode (APD) by combining sinusoidally balanced differencing and low-pass filtering techniques to minimize detrimental waveform distortion of the avalanche signal, and realize a 1-GHz gated InGaAs/InP single-photon detector with the timing jitter as low as 60 ps. The detection efficiency could reach 10.4% at 1550 nm with the maximum count rate ~100 MHz, after pulse probability ~3.0%, and dark count rate ~6.1 × 10-6 per gate. Such low timing jitter single-photon detectors offer facility for quantum key distribution at gigahertz clock rate.

High-speed InGaAs/InP-based single-photon detector with high efficiency

An efficient single-photon detector at telecom wavelength of 1.55 μm was realized with an InGaAs/InP avalanche photodiode at −30 °C. By implementing a short gating pulse and optimizing the self-differencing circuit, a detection efficiency of 29.3% was achieved with an error count probability of 6% at the gating frequency of 200 MHz, paving the way for the high-efficiency and low-noise fast detection of the infrared single photons.

Photon-number-resolving detection based on InGaAs/InP avalanche photodiode in the sub-saturated mode

We demonstrated a robust spike cancellation by virtue of optical balancing technique for the near-infrared single-photon detection based on InGaAs/InP avalanche photodiode. A 31 dB suppression of the spike noise provided an efficient technique to read out weak avalanche currents at the early built-up, allowing the study on the photon number resolving dynamics of the InGaAs/InP avalanche photodiode. With the detection efficiency varied from 1% to 36%, the avalanche gain was shown to vary from the linear mode to the saturated mode and evidenced as a sub-saturated avalanche state. Multi-photon avalanche saturation was observed at different photon numbers as the avalanche gain varied. A photon-number-resolving detection was achieved with the detection efficiency as high as 36%.

Two-bit quantum random number generator based on photon-number-resolving detection

Here we present a new fast two-bit quantum random number generator based on the intrinsic randomness of the quantum physical phenomenon of photon statistics of coherent light source. Two-bit random numbers were generated according to the number of detected photons in each light pulse by a photon-number-resolving detector. Poissonian photon statistics of the coherent light source guaranteed the complete randomness of the bit sequences. Multi-bit true random numbers were generated for the first time based on the multi-photon events from a coherent light source.

Quantum random-number generator based on a photon-number-resolving detector

We demonstrated a high-efficiency quantum random number generator which takes inherent advantage of the photon number distribution randomness of a coherent light source. This scheme was realized by comparing the photon flux of consecutive pulses with a photon number resolving detector. The random bit generation rate could reach 2.4 MHz with a system clock of 6.0 MHz, corresponding to a random bit generation efficiency as high as 40%. The random number files passed all the stringent statistical tests.

Room-Temperature Single-Photon Detector Based on InGaAs/InP Avalanche Photodiode With Multichannel Counting Ability

Using a capacitance balancing circuit, we achieved infrared single-photon detection based on an InGaAs/InP avalanche photodiode (APD) with a low dark count rate and negligible afterpulse effect at room temperature of 290 K. Detection efficiency of 9.80% was attained with the dark count rate of 6.62 × 10-4 per gate, showing that the detector could work efficiently even at room temperature without Peltier cooling. Moreover, the detector was operated in an arbitrary gated mode, meaning that more than one gating pulse was applied on the APD during one period. The single-photon detector working in this mode was capable of multichannel photon counting for practical quantum key distribution.

Optically Self-Balanced InGaAs–InP Avalanche Photodiode for Infrared Single-Photon Detection

We demonstrated a robust noise cancellation by using an optical self-differential technique for the near-infrared single-photon detection based on an InGaAs-InP avalanche photodiode, which enabled 31-dB suppression of the spike noise, resulting in a detection efficiency of 22.4% with an afterpulse probability of 2.4% at the gating frequency of 25 MHz. This technique may provide a promising way for high-efficiency and low-noise fast detection of infrared single photons.

Photon-number-resolving detection at 1.04 μm via coincidence frequency upconversion.

We demonstrated the photon-number-resolving detection at 1.04 μm by coincidence frequency upconverison. The detection efficiency of 6.8% was obtained. The Poissionian distribution of the up-converted photons was observed directly.

Time-dependent photon number discrimination of InGaAs/InP avalanche photodiode single-photon detector

We investigated the photon-number-resolving (PNR) performance of the InGaAs/InP avalanche photodiode (APD) as a function of the electric gate width and the photon arrival time. The optimal electric gate width was around 1 ns for PNR measurements in our experiment, which provided a PNR capability up to three photons per pulse when the detection efficiency was ~20%. And the dependence of the PNR performance on the arrival time of the photons showed that the photon number could be better resolved if the photons arrived on the rising edge of the electric gate than on the falling edge. In addition, we found that with the increase of the electric gate width, PNR performance got worse. The observation would be helpful for improving the PNR performance of the InGaAs/InP APD in the gated mode.

Linear External Optical Gain Photodetector at Few-Photon Level

Here we show that by using an external optical gain instead of electronic gain, a conventional photodiode was able to respond linearly to few-photon pulses. Few-photon pulses could be detected after amplification to ~ 104-photon pulses by stimulated emission in erbium-doped fiber amplifiers. The voltage amplitude of the peak output signal from the photodiode was proportional to the incident photon numbers and no saturation effects were observed. Such a linear external optical gain photodetector was implemented in an ultralow light interference experiment, showing its prospective potential application as a simple but robust solution for the ultralow optical detection.